Even when they end in the desired outcome of pregnancy, fertility treatments are complicated and carry certain risks. No, we're not talking about the risk of creating your own version of John & Kate Plus 8, though that is a possibility; we're talking about the fact that babies conceived using in vitro fertilization have a higher risk of having birth defects. This has been known for a while, but it's never been understood what caused it. Well, now a large new study has been completed that pinpoints the risk to one specific IVF treatment and finds that it's probably caused both by the underlying infertility and the procedure used by doctors. But as scary as that sounds, don't swear off fertility treatments for life just yet, since it turns out there are plenty of ways to lower your risks.

First it is important to know that there are two kinds of IVF. One involves simply commingling eggs and sperm in dish and waiting for them to fertilize each other—hence the term "test tube baby." The other kind, called intracytoplasmic sperm injection (say that three times fast), is a bit more complex. ICSI involves taking single sperm and injecting it right into an egg. It was originally developed for cases where male infertility (aka faulty sperm) played a role, but it is now commonly used simply to up the odds that at least some embryos will be created—and a lot of fertility clinics do it in all cases.

The study found that the risk of birth defects for simple IVF is the same as the risk for babies conceived naturally. So there's no danger in just holding a little sperm and egg party in a lab. However, when ICSI is used, about 10 percent of the babies conceived using IVF had birth defects compared with only six percent of the babies conceived naturally. In terms of how birth defect is defined in this case, we're talking serious problems:

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Researchers counted heart, spinal or urinary tract defects, limb abnormalities and problems such as cleft palate or lip, but not minor defects unless they needed treatment or were disfiguring.

Ten percent with these kinds of defects is nothing to sneeze at, especially when you consider that in the U.S. in 2009, there were more than 60,000 babies were born from 146,000 IVF attempts. Of that 60,000, about 75 percent of them were conceived using ICSI.

This study, which was done in Australia, is notable not only for being the first large scale study of this kind but also it's ability to analyze more precisely where the risk is coming from. It was conducted using records from more than 300,000 babies in Australia that were conceived naturally and more than 6,000 that were conceived using fertility treatments. The records span 1986 to 2002.

There's a whole variety of fertility treatments, running from simply taking medicine to boost egg production to artificial insemination to IVF. The study looked at how birth defect rates broke down by the type of treatments used, and they also compared groups of women who'd conceived naturally but had a history of infertility or had previously used assistance in getting pregnant. Of all of the groups, the only treatment that resulted in an increased risk of birth defects was the use of IVF involving ICSI.

So why is it particularly prone to resulting in birth defects? Well, there are two possibilities. First, it could be that the sperm are defective in some way, which might explain why they have trouble swimming to and fertilizing an egg on their own. Or it could be damage that results from the actual manhandling of the sperm or egg during the injection process itself. The study, however, found that babies who were conceived naturally by women who had a history of infertility (including previous assisted pregnancies) also had a higher rate of birth defects. This points to the fact that there is something about the infertility itself that's playing a role; it's not just the technological intervention in IVF that's to blame.

The other complicating factor here is that the study spans a 16-year time frame, and things have changed dramatically in that time. Dr. Joe Leigh Simpson, a geneticist and research chief at the March of Dimes, said ICSI may well be safer now than it was back in the late 80s. Thus, the risk might be much lower now, but that wouldn't necessarily show up in the study's conclusions.

Either way, while it's daunting to realize that such a common procedure carries extra risk, there no reason to throw the treatment out the window. For one thing, Michael Davies of the University of Adelaide, the study's lead author, says the reality is that most babies are born healthy, and there are plenty of ways to lessen the risk, even with ICSI. For another, those who don't need ICSI could forego it and opt for simple IVF. And yet option is to freeze the embryos that result from IVF (with or without sperm injection) and then implant a few at a time later rather than sticking them in there fresh out of the dish. While it sounds sort of counterintuitive, the process of freezing and thawing actually tends to destroy weak embryos and, since only fit embryos end up surviving and being implanted, it cuts down on the risk of birth defects.

Plus, even if the risk is slightly higher for ISCI, there are plenty of risks that come from naturally conceived pregnancies and from living in general that might result in you not getting a perfectly healthy baby. So there's really only so much fretting one can do if you're going to jump off the high dive into the pregnancy pool.